Coronary heart disease (“CHD”) is a disease in which the coronary arteries (blood vessels which feed oxygenated blood to the heart) become obstructed by the buildup of lipid-rich plaque. As plaque ages, it may become calcified, permanently narrowing the coronary arteries, or it may contribute to the formation of blood clots, which in turn can partially or fully obstruct the coronary arteries. In both cases, the flow of oxygen-rich blood to the heart is decreased, leading to angina (pain or discomfort in the chest) or heart attack.
There are two common treatments for CHD: angioplasty and coronary artery bypass grafting (“CABG”). Angioplasty is a non-surgical procedure in which a balloon catheter is threaded into a coronary artery and is used to widen obstructions caused by accumulations of plaque. Angioplasty may also involve the placement of a stent within narrowed portions of the coronary artery to improve the flow of blood within those portions. CABG, meanwhile, is the most common form of open heart surgery, in which a section of a healthy blood vessel is harvested from another portion of the body (for instance, the patient's internal mammary artery or a vein taken from the patient's leg) and grafted to form a link between a source of fresh oxygenated blood such as the aorta and the portion of the coronary artery downstream of the blockage. CABG, as currently practiced, involves open heart surgery (thoracotomy) or throacoscopy, and may also involve the use of a heart-lung bypass machine. While CABG is typically necessary in cases of CHD too severe to be treated effectively using angioplasty, the risks and costs associated with the CABG procedure are significantly greater than those presented by angioplasty.